I made one. It's ~1.75" thick and I guess 12"x20".

I use it with regular chefs knife and cleaver both. Has held up well. Chef's knife causes marking which are not deep. Cleaver leaves little deeper cuts.

In last 2 years I re-surfaced it once when it went out of flat. I give it a good scrub wash and oil it once in a while.

Initial cuts make it look bad. Lots of cut convert it into modern art.